Chore: don't make Linter a subclass of EventEmitter (refs #9161) (#9177)

lib/linter.js

@@ -731,10 +731,9 @@ const BASE_TRAVERSAL_CONTEXT = Object.freeze(
  * Object that is responsible for verifying JavaScript text
  * @name eslint
  */
-class Linter extends EventEmitter {
+class Linter {
 
     constructor() {
-        super();
         this.messages = [];
         this.currentConfig = null;
         this.currentScopes = null;
@@ -747,17 +746,13 @@ class Linter extends EventEmitter {
 
         this.rules = new Rules();
         this.environments = new Environments();
-
-        // set unlimited listeners (see https://github.com/eslint/eslint/issues/524)
-        this.setMaxListeners(0);
     }
 
     /**
      * Resets the internal state of the object.
      * @returns {void}
      */
     reset() {
-        this.removeAllListeners();
         this.messages = [];
         this.currentConfig = null;
         this.currentScopes = null;
@@ -859,6 +854,10 @@ class Linter extends EventEmitter {
             ast = this.sourceCode.ast;
         }
 
+        const emitter = new EventEmitter();
+
+        emitter.setMaxListeners(Infinity);
+
         // if espree failed to parse the file, there's no sense in setting up rules
         if (ast) {
 
@@ -939,7 +938,7 @@ class Linter extends EventEmitter {
 
                     // add all the selectors from the rule as listeners
                     Object.keys(rule).forEach(selector => {
-                        this.on(selector, timing.enabled
+                        emitter.on(selector, timing.enabled
                             ? timing.time(ruleId, rule[selector])
                             : rule[selector]
                         );
@@ -972,9 +971,7 @@ class Linter extends EventEmitter {
             // augment global scope with declared global variables
             addDeclaredGlobals(ast, this.currentScopes[0], this.currentConfig, this.environments);
 
-            let eventGenerator = new NodeEventGenerator(this);
-
-            eventGenerator = new CodePathAnalyzer(eventGenerator);
+            const eventGenerator = new CodePathAnalyzer(new NodeEventGenerator(emitter));
 
             /*
              * Each node has a type property. Whenever a particular type of